In general, structuring agents for dispersions are known. For a long time fatty compositions have existed that work as a dispersion structuring agent in edible water-in-oil emulsions, such as margarines and spreads. These edible dispersions typically have an oil phase that is a blend of liquid oil and fat that is solid at normal ambient temperature (20° C.). This solid fat, often also designated as hardstock, acts as a structuring agent, and its function is to stabilize the dispersion. To this end, traditionally, the dispersion is made by a process involving a temperature at which the oil phase, including the hardstock, is liquid, followed by cooling so as to form a fat crystal network that works to stabilize the dispersions and that lends some degree of firmness to the resulting product.
In WO 2005/014158 some drawbacks of the traditional hardstock, structuring agents are addressed. E.g., heating and cooling steps are involved that need to be applied to the whole weight of the dispersion, which requires a relatively high amount of energy. Further, the choice of suitable fats is relatively limited, as many fats will have inappropriate melting points to form a stabilizing crystal network at the appropriate temperature. In order to address these drawbacks, fine solid fat particles are employed as a structuring agent. These particles are preferably prepared by micronization. The disclosed process involves preparing a homogeneous mixture of structuring agent and liquefied gas or supercritical gas at a pressure of 5 to 40 MPa, and expanding the mixture through an orifice, under such conditions that a spray jet is applied in which the structuring agent is solidified and micronized.
As a further background on micronization of fats, U.S. Pat. No. 6,056,791 is referred to. This describes the preparation of micronized fat particles by dissolution of gas (carbon dioxide) in the fat under pressure, and decompressing the mixture in such a way that the temperature falls below the solidification point of the fat, so that micronized particles are formed.
Although the use of micronized fat as a structuring agent solves some of the aforementioned drawbacks of the traditional structuring agents, this does not mean that always as good a dispersion structuring is obtained as with the formation of a fatty crystal network through heating and subsequent cooling. Also, the powders formed by the micronization of fat are very fine, and may be difficult to handle during further processing. Moreover, despite this processing drawback, it is desired to use even finer particles, as the resulting higher surface area will contribute to the dispersion structuring capability of such particles.
Particle generation with supercritical CO2 is an area of attention in many fields of technology. See e.g. E. Lack et al. Particle Generation with Supercritical CO2, 1st Vienna International Conference: Micro- and Nano-Technology (2005). Herein a variety of particles is illustrated, including fat encapsulated water.